Indicating instrument.



Patented N ov l9, l90l T; F. MULLANEY, INDIGATING INSTRUMENT.

(Application pm Aug. 16, 1901.

(No Model.)

Inventor Thomas F. mullcmeg.

WiGnesses.

THE mama PETERS co, PHOTO-UTHQ. WASNINOYON, u. c.

accordingly.

NITED STATES PATENT OFFICE.

THOMAS F. MULLANEY, OF NEW YORK, N. Y., ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

INDICATINGI SPECIFICATION forming part of Letters Patent N 0. 687,050,dated November 19, 1901.

Application filed August 16, 1901. Serial No. 72,288. (No model.)

To all whom it may concern:

Be it known that I, THOMAS F. MULLANEY, a citizen of the United States,residing at New York, in the county of New York, State of New York, haveinvented certain new and useful Improvements in Indicating Instru ments,(Case No. 2,193,) of which the following is a specification.

My present invention relates to an arrangement of indicating deviceswhich is particularly valuable in connection with the synchronizing ofalternating-current dynamoelectric machines, although not, however,limited to use in this relation only.

In synchronizing-machines of the character mentioned it is becoming acommon prac-' tice to employ two indicating instruments, such asvoltmeters, one of the voltmeters-being connected so as to have zerodeflection when the machines are in synchronism and the other soconnected as to have a deflection ofsome determinate amount, dependentupon the voltage of the machines. To determine the proper instant tothrow the machines together, it is necessary to observe both voltmetersas nearly simultaneously as possible and to throw the machines togetherwhen one voltmeter reads zero and the othera value dependent upon thevoltage of the machines. By my present invention this operation is muchsimplified and consists, briefly, in mounting thevoltmeters together,sothat their pointers move either over the same scale or at least so thattheir relative positions may be readily compared. The relative positionsof the two voltmeters is made such that the pointer of one when it readszero is located close to the pointer of the other voltmeter when thelatter is in the position corresponding to synchronism between themachines. In case the voltage of the machines is changed it is evidentthat the position of the needle at the last-mentioned voltmeter willchange I therefore provide means whereby the needles of the twovoltmeters may be brought together at this new voltage, whatever it maybe. This means preferably consists in mounting one of the voltmeters sothat it may move bodily with respect to the other, thereby securing therelative adjustment desired.

The scope of my invention is set forth in claims appended hereto, whilethe details of construction and arrangement of one embodiment of myinvention are set forth in the following description,which is to betaken in connection with the accompanying drawing.

Referring'to the drawing, 1, 2, and 3 indicate bus-bars of thethree-phase system, to which is shown connected a three-phase generator,(indicated diagrammaticallyat 4.) A second three-phase generator issimilarly indicated at 5; but the switches 6 7 8, which are adapted toconnect it to the bus-bars, are represented in their open position.

In order to determine when the two machines 4 and 5 are in synchronismwith each other, two voltmeters 9 and 10 are employed. The voltmeter 9is connected across secondary windings 11 12 in series with each other.The primary windings 13 14, corresponding to the secondaries mentioned,are connected across corresponding phases of the respective machines 45, the winding 13 being shown as connected across the phase a b of themachine 4 and the primary 14 across the phase a b of the machine 5. Whenthese two machines are in synchronism, it will be evident that theelectromotive forces of the windings 11 and 12 will either exactlycounterbalance each other or will be addedtogether, dependent upon howthe windings are joined in series.

In the present instance the windings are sup posed to be connected sothat their electromotive forces neutralize each other, thereby givingzero deflection of the voltmeter 9 when the machines are in synchronism.The reading of this voltmeter, however, is not sufficiently sensitive toindicate with accuracy the instant of synchronism between the machines 4and 5, but is employed to determine whether the machines are in conjunctionor opposition to each other, a state of affairs between which thesynchronizing-voltmeter 10 does not discriminate. This latter voltmeter10 is connected across two series-connected secondaries 12 15, theprimaries 14 and 16 of which are the primary 16 is connected across thenoncorresponding phase a c of the machine 4. When the machines are insynchronism, the voltmeter 10 will have a deflection corresponding tothe resultant of the electrometive forces across the phases a b and a cof the respective machines.

In the drawing, the voltmeter-needle 17 of the voltmeter 10 isrepresented as having a deflection which may be assumed to be that whichwould exist when the machines 4 and 5 are in synchronism. In a similarmanner the needle 18 of the voltmeter 9 is represented ashaving zerodeflection, showing that the machines are in conjunction with eachother. In order to recognize these conditions at a glance, the voltmeter9 may be rotated bodily in bearings or other supports 19, so as to bringthe needle 18 in its zero position directly over the position occupiedby the needle 17 of the other voltmeter when the machines are runningsynchronously. Under these conditions the instant of synchronism isshown whenever the needles coincide in position. In case it be desiredto synchronize the machines with diiferent voltages, the voltmetcrs willrequire different relative adjustment, as will readily be understoodWithout further explanation. It will of course be evident that thisadjustment may be secured in a wide variety of ways and is not limitedto the exact arrangement shown. Thus, for example, the voltmeter 9 mightbe stationary and the voltmeter l0 adjustable, or both voltmeters mightbe relatively fixed, and a needle of one or the other adjustable on itsshaft. Various other arrangements will suggest themselves to one skilledin the art. Moreover, it will of course be evident that the inventionmay be used with ma chines of any number of phases and is not limited touse in connection with three-phase machines only.

lVhat I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. In a synchronizing device, the combination of two voltmeters arrangedso that the needles of both move in proximity to each other, and meansfor relatively adjusting the position of one voltmeter-needle withrespect to the other.

2. In a synchronizing device, the combination of two voltmeter-sarranged so as to have their needles or pointers movein proximity toeach other, means for causing the deflection of one voltmeter torepresent the resultant of voltages corresponding respectively to likephases of the machines to be synchronized, and means for causing thedeflection of the other voltmeterto represent the resultant ofelectromotive forces corresponding respectively to unlike phases of saidmachines.

3. The combination of superposed voltmeters, and means for adjusting themoving element of one voltmeter relatively to the moving element of theother voltmeter.

4. A synchronism-indicating device consisting of two voltmeters havingneedles arranged to move either over the same scale or into proximity toeach other, and means for causing the needles to come together whensynchronism is attained.

5. A synchronism-indicating device consisting of two voltmeters havingthe ends of their pointers or needles movable either over the same scaleor into proximity to each other, means for causing a zero deflection ofone voltmeter at synchronism and a predetermined defiection of the othervoltmeter at synchronism, and means for relatively adj usting thevoltmeters or parts thereof so that the pointer or needle of one is inclose proximity to the other when synchronism exists.

In witness whereof I have hereunto set my hand this 14th day of August,1901.

THOMAS F. MULLANEY.

Witnesses:

BENJAMIN B. H LL, MARGARET E. WOOLLEY.

